C++ primer第五版 第十章编程练习拓展（链表）

问题描述：

       创建一个链表类，该链表对象具有插入节点至特定位置（或头结点）、查询节点对象、删除节点对象、返回节点长度等功能。节点的功能为：包含学生信息（姓名，ID）和节点指针（指向下一节点）。

功能实现：

list.h

#pragma once
#ifndef LIST_H_
#define LIST_H_
//创建string 类头文件
#include<string>
using namespace std;

struct Info
{
	string name;
	int id;
};

struct Node
{
	Info val;
	Node *next;
	Node(Info x) :val(x), next(NULL) {}
};

class List
{
private:
	Node * head;
	int length;
public:
	List();
	~List();
	int len();
	int find(const Info val);
	void insert(Info val, int n = 0);
	void remove(Info val);
	void print();
};
#endif

list.cpp

#include<iostream>
#include"list.h"

using namespace std;

List::List()
{
	head = NULL;
	length = 0;
}

List::~List()
{
	Node *temp;
	for (int i = 0; i < length; i++)
	{
		temp = head;
		head = head->next;
		delete temp;
	}
}

int List::len()
{
	return length;
}

int List::find(const Info val)
{
	Node *temp = head;
	int index = 1;
	while (temp != NULL)
	{
		if (temp->val.name == val.name && temp->val.id == val.id)
		{
			return index;
		}
		temp = temp->next;
		index++;
	}
	return -1;
}

void List::insert(Info val, int n)
{
	if (n < 0)
	{
		cout << "the n must be greater than or equal to zero. " << endl;
		return;
	}
	int index = 1;
	Node *temp = head;
	Node *node = new Node(val);
	if (n == 0)
	{
		node->next = head;
		head = node;
		length++;
		return;
	}
	while (temp != NULL && index < n)
	{
		temp = temp->next;
		index++;
	}
	if (temp == NULL)
	{
		cout << "insert fail !" << endl;
		return;                                           //避免空指针异常
	}
	node->next = temp->next;
	temp->next = node;
	length++;
}

void List::remove(Info val)
{
	int n = find(val);
	if (n == -1)
	{
		cout << "remove fail ! " << endl;
		return;                                          //避免空指针异常 
	}
	if (n == 1)
	{
		head = head->next;
		length--;
		return;
	}
	int index = 2;
	Node *temp = head;
	while (index < n)
	{
		temp = temp->next;
	}
	temp->next = temp->next->next;
	length--;
}

void List::print()
{
	if (head == NULL)
	{
		cout << "list is already empty ! " << endl;
		return;                                        //避免空指针异常
	}
	Node *temp = head;
	while (temp != NULL)
	{
		cout << temp->val.name << " , " << temp->val.id << endl;
		temp = temp->next;
	}
	cout << endl;
}

功能验证：

main.cpp

#include<iostream>
#include"list.h"

using namespace std;

int main()
{
	List list;
	Info items[5] = { { "Alpha", 1 },{ "Beta",2 },{ "Cigma", 3 },{ "Delta", 4 },{ "Epsilon",5 } };

	cout << "insert test: " << endl;
	for (int i = 0; i < 5; i++)
	{
		list.insert(items[i]);
	}
	cout << "The list length is : " << list.len() << endl;
	list.print();
	
	cout << "--------------*---------------" << endl;
	list.insert(items[2]);
	list.insert(items[1], 4);
	list.insert(items[1],1);
	cout << "the list length is : " << list.len() << endl;
	list.print();
	
	cout << "remove test: " << endl;
	list.remove(items[2]);
	cout << "The list length is : " << list.len() << endl;
	cout << "-----------------***------------" << endl;
	list.print();

	list.remove(items[4]);
	cout << "The list length is : " << list.len() << endl;
	list.print();
	cout << "-----------------****------------" << endl;
	return 0;
}

【注：linux环境编译，可能的异常：（dump core）,主要原因为空指针异常，因此需要添加return；】

参考文章：c++实现链表基本操作